Single-use or disposable systems are rapidly increasing in biopharmaceutical industry due to the flexibility and cost-effectiveness of such systems. Disposable components in the systems are presterilized and qualified to regulatory requirements. Disposable systems are easy to adapt to different production purposes and it is easy and inexpensive to change a product line while good process reliability is at least maintained, if not even improved.
There are several kinds of mixing systems in which disposable containers or bags may be used. One type of such mixing system is a bioreactor in which cells or microorganisms can grow. Mixing systems are also used to prepare for example buffer and media. The mixing systems may comprise a support compartment which houses a disposable bag or container. The compartment may have a form of a cylinder, for example a substantially circular cylinder. The bag is placed inside the compartment in an accurate manner so that for example different pipelines, mixers and sensors can be connected to the bag properly and accurately. US2011/0310696 shows a mixing system of this kind
For cell cultivation it is necessary to provide agitation in order to keep the cells suspended and to provide convective mass transport of nutrients, gases and metabolites. In larger bags, such as bags for use in support compartments, agitation is normally provided by a rotating agitator. To prevent vortexing it is then desirable to have one or more vortex breakers in the bag. WO2012/015571 describes a type of vortex breaker which is made from a sheet of plastic material extending from the bag walls across the bag. This arrangement has a drawback in that stagnant pockets are formed at the vortex breaker-bag wall interface, where cells and/or microcarriers with cells may accumulate. This applies in particular to pockets adjacent to the bottom wall of the bag. Accumulation of cells is undesirable as the cultivation conditions may deteriorate locally and signal substances released from the accumulated cells can affect the entire culture. Further, a vortex breaker extending horizontally across the bag as in WO2012/015571 will disturb the convective flow inside the bag.
Accordingly there is a need for a vortex breaker in collapsible vessels which does not form stagnant pockets and which enables a good convective flow.